Self-aligning swaging punch and method for swaging

ABSTRACT

A self-aligning swaging punch is provided for adjoining together a pin and a workpiece having a pinhole. The swaging punch comprises a shaft and a tip having an open-ended cavity. The shaft transfers an axial force from a press or hammer to the tip. The tip transfers the axial force from the shaft to a top surface of the workpiece near the pinhole. The tip may be spherical in shape for evenly deforming the workpiece near the upper edge of the pinhole. The open-ended cavity receives the pin therein and allows the pin to extend at least partially into the open-ended cavity while the tip contacts the workpiece. The open-ended cavity also ensures that the swaging punch is aligned with the pinhole and perpendicular to the surface of the workpiece when the pin is inserted into the pinhole such that the workpiece evenly deforms and presses against the pin.

RELATED APPLICATIONS

This patent application is a divisional, and claims priority benefitwith regard to all common subject matter, of earlier-filed U.S. patentapplication Ser. No. 15/897,240, filed on Feb. 15, 2018, and entitled“SELF-ALIGNING SWAGING PUNCH AND METHOD FOR SWAGING”. Application Ser.No. 15/897,240 is a divisional of earlier-filed U.S. patent applicationSer. No. 14/862,990, filed on Sep. 23, 2015, and entitled “SELF-ALIGNINGSWAGING PUNCH AND METHOD FOR SWAGING”. The identified earlier-filedpatent applications are hereby incorporated by reference in theirentireties into the present application.

BACKGROUND

Swaging is often used for affixing a pin or similar member to aworkpiece. For example, swaging is often used to affix high-densityradiopaque pins to workpiece subassemblies for identifying the locationof the workpiece subassemblies in assembled units via radiography.Swaging is also often used during assembly procedures for temporarilyaffixing adjoining members. Swaging is conventionally performed by usinga hand-held hammer to impact a sharp-tipped swaging punch that in turnplastically deforms material of a workpiece near the pin. The punch isrepositioned and impacted at other points around the pin until theworkpiece is sufficiently deformed. The deformed workpiece imparts apermanent compressive force on the pin or other member. However, thistechnique often yields inconsistent results due to inaccurate and randomswaging punch placement and highly variable punch impact forces.Inaccurate swaging can damage the workpiece or ineffectively secure thepin to the workpiece.

SUMMARY

The present invention solves the above-described problems and provides adistinct advance in the art of swaging tools. More particularly, thepresent invention provides a self-aligning swaging punch that ensures aneven swage around a workpiece and a repeatable swaging force applied tothe workpiece.

An embodiment of the self-aligning swaging punch may be used for swaginga pin into a pinhole of a workpiece. The swaging punch broadly includesa shaft and an inwardly-tapered tip.

The shaft transfers axial force to the inwardly-tapered tip. The shaftmay be substantially cylindrical or radially symmetrical and may beformed of tool-grade steel or other similar high-strength material.

The inwardly-tapered tip transfers the axial force from the shaft to aworkpiece and may include an upwardly extending open-ended cavity. Thetip may be spherical, frusto-conical, oblong, or any other suitableinwardly-tapered shape. Alternatively, the tip may have an orthogonalcross section. The tip may be an extension or an integral part of theshaft and may be formed of tool-grade steel or other similarhigh-strength material.

The open-ended cavity is formed in the distal end of the tip or shaftand receives at least a portion of a pin therein. The open-ended cavitymay be cylindrical (circular cross section) or any other suitable shapefor restricting sideways movement of the pin within the open-endedcavity. The open-ended cavity may have a diameter that is slightlylarger than the diameter of the pin but slightly smaller than thediameter of the pinhole in the workpiece.

Use of the swaging punch will now be summarized. First, a pin may beinserted into the open-ended cavity. The swaging punch may then bepositioned near a pinhole of a workpiece such that the pin is at leastpartially inserted into the pinhole. The tip of the swaging punch maycontact the top surface of the workpiece near an edge of the workpieceextending around the top of the pinhole. The open-ended cavity willensure that the swaging punch is aligned with the pin and isperpendicular to the top surface of the workpiece. A controlled coaxialforce may then be applied to the shaft of the swaging punch such thatthe tip presses against the top surface of the workpiece near the edge.The contoured tip will deform the material of the workpiece near theedge such that some of the material deflects radially inwardly into thepinhole against the pin. This will create an interference fit betweenthe pin and the workpiece. The workpiece will thus exert an inward forceon the pin so as to retain the pin in the pinhole after the swagingpunch is removed.

The above-described swaging punch provides several advantages overconventional swaging systems. The shape of the tip ensures that thematerial deforms evenly into the pinhole around the pin. The open-endedcavity aligns the swaging punch and the pin perpendicularly with theouter surface of the workpiece. This ensures that the coaxial force isevenly transferred to the outer surface of the workpiece near the edgeof the pinhole. The swaging punch could be used with a punch press orsimilar device having a force gauge for swaging additional pins with thesame amount of force.

Another embodiment of the self-aligning swaging punch includes a plugcavity and a center-finder plug. The center-finder plug may be acylindrical plug or other similar free-moving member that may shift intoand out of the plug cavity. For example, the center-finder plug and theplug cavity may have complementary square or rectangular cross sectionsor any other shape. The center-finder plug may extend into the pinholewhen the open-ended cavity and the pinhole are aligned with each other.The material of the workpiece may be deformed so as to press against thecenter-finder plug instead of the pin, thus securing the pin in thepinhole.

The above-described swaging punch provides several advantages overconventional swaging systems. For example, the center-finder plugensures that the swaging punch is aligned with the pinhole. Thecenter-finder plug also allows the pin to be secured in the pinholewithout any portion of the pin extending beyond the outer surface of theworkpiece.

Yet another embodiment of the self-aligning swaging punch includes aplug cavity and center-finder plug that both narrow towards their distalends. For example, the plug cavity may have a frusto-conical shape whilethe center-finder plug may have a conical shape. The conical ornarrowing shape of the center-finder plug will allow the center-finderplug to gradually extend farther out from the plug cavity when theswaging punch moves into alignment with the pinhole. Similarly, theconical or narrowing shape of the center-finder plug will allow the edgeof the workpiece to gradually urge the center-finder plug into the plugcavity when the swaging punch moves out of alignment with the pinhole.The center-finder plug will extend farthest from the plug cavity whenthe swaging punch is aligned with the pinhole.

The above-described swaging punch provides several advantages overconventional swaging systems. For example, the center-finder plugensures that the swaging punch is aligned with the pinhole whileallowing the swaging punch to be slid along the outer surface of theworkpiece into alignment with the pinhole.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present invention will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a cutaway perspective view in partial section of a swagingpunch constructed in accordance with an embodiment of the presentinvention;

FIG. 2 is a vertical section view of the swaging punch of FIG. 1;

FIG. 3 is a vertical section view of a swaging punch constructed inaccordance with another embodiment of the present invention; and

FIG. 4 is a vertical section view of a swaging punch constructed inaccordance with yet another embodiment of the present invention.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the present technology can include a variety of combinationsand/or integrations of the embodiments described herein.

Turning now to the drawing figures, and particularly FIGS. 1 and 2, aself-aligning swaging punch 10 (hereinafter “swaging punch 10”)constructed in accordance with an embodiment of the invention isillustrated. The swaging punch 10 may be used for affixing a pin to aworkpiece and broadly comprises a shaft 12 and an inwardly-tapered tip14.

The shaft 12 transfers axial force to the tip 14 and may besubstantially cylindrical or radially symmetrical for imparting an evenand balanced axial force to the tip 14. The shaft 12 may include ahandle or adaptor geometry for inserting the shaft 12 into the chuck ofa punching machine, pressing machine, drill press, or any other suitablemachine. The shaft 12 may be formed of tool-grade steel or other similarhigh-strength material.

The inwardly-tapered tip 14 (hereinafter “tip 14”) transfers the axialforce from the shaft 12 to a workpiece 100 and may include an open-endedcavity 16. The tip 14 may be spherical, frusto-conical, oblong, or anyother suitable inwardly-tapered shape. Alternatively, the tip 14 mayhave an orthogonal cross section for use with square or rectangular pinsand pinholes. It will be understood that the tip 14 may be any suitableshape for swaging pins and pinholes of any size and shape. For example,the tip 14 may be a tapered circular, rectangular, square, or hexagonalshape or any other shape. The tip 14 may be an extension or an integralpart of the shaft 12 and may be formed of tool-grade steel or othersimilar high-strength material.

The open-ended cavity 16 receives at least a portion of a pin 200therein and extends upwardly into the tip 14 and/or shaft 12. Theopen-ended cavity 16 may be cylindrical (circular cross section) or anyother suitable shape for restricting sideways movement of the pin 200within the open-ended cavity 16. The open-ended cavity 16 may have adiameter that is slightly larger than the diameter of the pin 200 butslightly smaller than the diameter of a pinhole 104 in the workpiece100. The open-ended cavity 16 may be coaxially aligned with the tip 14such that the shaft 12 and tip 14 are coaxially aligned with the pin 200when the pin 200 is positioned in the open-ended cavity 16. Theopen-ended cavity 16 may be shorter than the pin 200 such that the pin200 will at least partially extend from the tip 14 when fully insertedinto the open-ended cavity 16.

Use of the swaging punch 10 will now be described in more detail. First,the pin 200 may be inserted at least partially inserted into theopen-ended cavity 16. The swaging punch 10 may then be positioned nearthe pinhole 104 of the workpiece 100 such that the pin 200 is at leastpartially inserted into the pinhole 104. The tip 14 of the swaging punch10 may also contact the top surface 102 of the workpiece 100 near anupper edge 106 of the pinhole 104. The open-ended cavity 16 will ensurethat the swaging punch 10 is aligned with the pin 200 and isperpendicular to the top surface 102 of the workpiece 100. A controlledcoaxial force may then be applied to the shaft 12 of the swaging punch10 such that the tip 14 of the swaging punch 10 presses against the topsurface 102 of the workpiece 100 near the edge 106. The tip 14 willdeform the material of the workpiece 100 near the edge 106 such thatsome of the material deflects radially inwardly into the pinhole 104against the pin 200 so as to create an interference fit between the pin200 and the workpiece 100 at high stress areas, as shown in FIG. 2. Notethe high stress areas within the dashed lines of FIG. 2. The workpiece100 will thus exert an inward radial force on the pin 200 so as toretain the pin 200 in the pinhole 104 after the swaging punch 10 isremoved. The coaxial force may be manually controlled or monitored via aforce gauge. The swaging punch 10 may then be pulled away from theworkpiece 100 and the pin 200. The swaging punch 10 may then be re-usedby inserting another pin 200 in the open-ended cavity 16.

The above-described swaging punch 10 provides several advantages overconventional swaging systems. For example, the shape of the tip 14ensures that the material deforms evenly into the pinhole 104 around thepin 200. The open-ended cavity 16 perpendicularly aligns the swagingpunch 10 and the pin 200 with the outer surface 102 of the workpiece100. This ensures that the coaxial force is evenly transferred to theouter surface 102 of the workpiece 100 near the edge 106 of the pinhole104. The open-ended cavity 16 is sized to snugly receive the pin 200while allowing the swaging punch 10 to be removed when the pin 200 issecured in the pinhole 104. The swaging punch 10 may be reused and doesnot require the use of power tools or elaborate machine setups. Theswaging punch 10 may be designed to meet a variety of radial contactpressures and pullout force requirements and may be used with metallicand polymeric materials and any other relatively malleable material. Useof a force gauge to monitor the axial force will ensure that a desiredamount of force is applied to the workpiece 100 and that each swagingprocess is performed uniformly.

A self-aligning swaging punch 300 constructed in accordance with anotherembodiment of the present invention is similar to the swaging punch 10described above except that the open-ended cavity is a plug cavity 302for receiving a sacrificial center-finder plug 304 therein, as shown inFIG. 3. The center-finder plug 304 may be a cylindrical plug or othersimilar free-moving member configured to shift into and out of the plugcavity 302. For example, the center-finder plug 304 and the plug cavity302 may have complementary circular, rectangular, square, or hexagonalcross sections or any other shape.

In use, the swaging punch 300 may retain the center-finder plug 304entirely in the plug cavity 302 such that the tip of the swaging punch300 may be moved against the outer surface 102 of the workpiece 100 withthe center-finder plug 304 being positioned within the plug cavity 302.The center-finder plug 304 may then shift or fall at least partially outof the plug cavity 302 at least partially into the pinhole 104 when thecenter-finder plug 304 (and the plug cavity 302) are aligned with thepinhole 104. Once the swaging punch 300 is aligned with the pinhole 104,a force may be applied to the swaging punch 300 as described above, suchthat some of the material of the workpiece 100 near the edge 106 of thepinhole 104 is urged inwards against the center-finder plug 304 and/orthe pin 200. That is, the center-finder plug 304 may retain the pin 200in the pinhole 104 via the interference fit between the center-finderplug 304 and the workpiece 100. Alternatively, the center-finder plug304 may be small enough to be retrieved from the pinhole 104 while thepin 200 is retained in the pinhole 104 via the inwardly-deformedmaterial of the workpiece 100.

The above-described swaging punch 300 provides several advantages overconventional swaging systems. For example, the center-finder plug 304ensures that the swaging punch 300 is aligned with the pinhole 104. Thecenter-finder plug 304 allows the pin 200 to be secured in the pinhole104 without any portion of the pin 200 extending beyond the outersurface 102 of the workpiece 100. In addition, the center-finder plug304 may be retained in the pinhole 104 such that the pin 200 is notexposed. Preventing the pin 200 from being exposed may be beneficial ina number of swaging applications.

A self-aligning swaging punch 400 constructed in accordance with yetanother embodiment of the present invention is similar to the swagingpunch 300 described above except that the swaging punch 400 includes aplug cavity 402 that narrows towards its opening and a center-finderplug 404 that narrows towards its distal end, as shown in FIG. 4. Theplug cavity 402 may be frusto-conical or any other similar shape thatcomprises a larger interior and a narrower or narrowing neck. Thecenter-finder plug 404 may be conical or any other similar shape thathas a larger base width or base diameter and a smaller or narrowingdistal end. The narrower opening of the plug cavity 402 retains thecenter-finder 404 at least partially in the plug cavity 402 such thatthe plug cavity 402 remains in the tip of the swaging punch 400.

In use, the swaging punch 400 may retain the center-finder plug 404entirely in the plug cavity 402 such that the tip of the swaging punch400 may be moved against the outer surface 102 of the workpiece 100 withthe center-finder plug 404 being positioned within the plug cavity 402.The conical or narrowing shape of the center-finder plug 404 will allowthe center-finder plug 404 to gradually extend farther out from the plugcavity 402 when the swaging punch 400 moves into alignment with thepinhole 104. Similarly, the conical or narrowing shape of thecenter-finder plug 404 allows the edge 106 of the workpiece 100 togradually urge the center-finder plug 404 into the plug cavity 402 whenthe swaging punch 400 moves out of alignment with the pinhole 104. Thecenter-finder plug 404 will extend farthest from the plug cavity 402when the swaging punch 400 is aligned with the pinhole 104, as shown inFIG. 4. A force may then be applied to the swaging punch 400 asdescribed above, such that some of the material of the workpiece 100near the edge 106 of the pinhole 104 is urged inwards into the pinhole104. In this embodiment, the center-finder plug is retained in the plugcavity 402 and will not become lodged in the pinhole 104. Meanwhile, thepin 200 is retained in the pinhole 104 via the inwardly-deformedmaterial of the workpiece 100.

The above-described swaging punch 400 provides several advantages overconventional swaging systems. For example, the center-finder plug 404ensures that the swaging punch 400 is aligned with the pinhole 104 whileallowing the swaging punch 400 to be slid along the outer surface 102 ofthe workpiece 100 into alignment with the pinhole 104. The center-finderplug 404 allows the pin 200 to be secured in the pinhole 104 without anyportion of the pin 200 extending beyond the outer surface 102 of theworkpiece 100. In addition, the center-finder plug 404 is not retainedin the pinhole 104 and instead remains in the tip of the swaging punch400.

Although the invention has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A self-aligning swaging punch for affixing a pin to aworkpiece having a pinhole, the self-aligning swaging punch comprising:a shaft having a proximal end and a distal end; an inwardly-tapered tipextending from the distal end of the shaft and having a contact end andan open-ended cavity extending upwardly from the contact end; and a plugpositioned in the open-ended cavity, the plug being configured toprotrude farther from the open-ended cavity when the open-ended cavitycomes closer into alignment with the pinhole and to be displaced upwardsinto the open-ended cavity when the open-ended cavity deviates fromalignment with the pinhole such that the plug protrudes farthest fromthe open-ended cavity when the open-ended cavity is aligned with thepinhole, the contact end of the inwardly-tapered tip being configured todeform an upper edge of the pinhole radially inwardly when theopen-ended cavity is aligned with the pinhole, the contact end ispositioned near the upper edge of the pinhole, and a coaxial force isapplied to the shaft so as to secure the pin at least partially in thepinhole.
 2. The self-aligning swaging punch of claim 1, wherein theopen-ended cavity has an inverted frusto-conical shape.
 3. Theself-aligning swaging punch of claim 1, wherein the plug has an invertedconical shape.
 4. The self-aligning swaging punch of claim 1, whereinthe plug has an outer surface and the inwardly-tapered tip has an innersurface, the outer surface and the inner surface being slanted at acommon angle.
 5. The self-aligning swaging punch of claim 1, wherein theplug has a distal end that terminates at a point.
 6. The self-aligningswaging punch of claim 1, wherein the inwardly-tapered tip issemi-spherical.
 7. The self-aligning swaging punch of claim 1, whereinthe plug has a proximal end and the end of the open-ended cavity isnarrower than the proximal end of the plug so that the open-ended cavityretains the plug at least partially therein.
 8. The self-aligningswaging punch of claim 1, wherein the plug is centered with theinwardly-tapered tip when the plug is at its farthest protrusion.
 9. Theself-aligning swaging punch of claim 1, wherein the plug, the contactend of the inwardly-tapered tip, and the open-ended cavity have radialsymmetry.
 10. The self-aligning swaging punch of claim 1, wherein theplug is configured to be retained entirely in the open-ended cavity. 11.A self-aligning swaging punch for affixing a pin to a workpiece having apinhole, the self-aligning swaging punch comprising: a shaft having aproximal end, a distal end, and a longitudinal axis; an inwardly-taperedtip extending from the distal end of the shaft and having a contact endand an open-ended cavity extending upwardly from the contact end, thecontact end forming a ring concentric with and perpendicular to thelongitudinal axis of the shaft for contacting the workpiece; and a plugpositioned in the open-ended cavity, the plug being configured toprotrude farther from the open-ended cavity when the open-ended cavitycomes closer into alignment with the pinhole and to be displaced upwardsinto the open-ended cavity when the open-ended cavity deviates fromalignment with the pinhole such that the plug protrudes farthest fromthe open-ended cavity when the open-ended cavity is aligned with thepinhole, the contact end of the inwardly-tapered tip being configured todeform an upper edge of the pinhole radially inwardly when theopen-ended cavity is aligned with the pinhole, the contact end ispositioned near the upper edge of the pinhole, and a coaxial force isapplied to the shaft so as to secure the pin at least partially in thepinhole.
 12. The self-aligning swaging punch of claim 11, wherein theopen-ended cavity has an inverted frusto-conical shape.
 13. Theself-aligning swaging punch of claim 11, wherein the plug has aninverted conical shape.
 14. The self-aligning swaging punch of claim 11,wherein the plug has an outer surface and the inwardly-tapered tip hasan inner surface, the outer surface and the inner surface being slantedat a common angle.
 15. The self-aligning swaging punch of claim 11,wherein the plug has a distal end that terminates at a point.
 16. Theself-aligning swaging punch of claim 11, wherein the inwardly-taperedtip is semi-spherical.
 17. The self-aligning swaging punch of claim 11,wherein the plug has a proximal end and the end of the open-ended cavityis narrower than the proximal end of the plug so that the open-endedcavity retains the plug at least partially therein.
 18. Theself-aligning swaging punch of claim 11, wherein the plug is centeredwith the inwardly-tapered tip when the plug is at its farthestprotrusion.
 19. The self-aligning swaging punch of claim 11, wherein theplug is configured to be retained entirely in the open-ended cavity. 20.A self-aligning swaging punch for affixing a pin to a workpiece having apinhole, the self-aligning swaging punch comprising: a shaft having aproximal end, a distal end, and a longitudinal axis; a semi-sphericalinwardly-tapered tip extending from the distal end of the shaft andhaving a contact end and an open-ended cavity extending upwardly fromthe contact end and having an inverted frusto-conical shape, the contactend forming a ring concentric with and perpendicular to the longitudinalaxis of the shaft for contacting the workpiece; and a plug beingconfigured to be retained entirely in the open-ended cavity and havingan inverted conical shape, the plug being configured to protrude fartherfrom the open-ended cavity when the open-ended cavity comes closer intoalignment with the pinhole and to be displaced upwards into theopen-ended cavity when the open-ended cavity deviates from alignmentwith the pinhole such that the plug protrudes farthest from theopen-ended cavity when the open-ended cavity is aligned with thepinhole, the shaft, the inwardly-tapered tip, and the plug having radialsymmetry; the contact end of the inwardly-tapered tip being configuredto deform an upper edge of the pinhole radially inwardly when theopen-ended cavity is aligned with the pinhole, the contact end ispositioned near the upper edge of the pinhole, and a coaxial force isapplied to the shaft so as to secure the pin at least partially in thepinhole.